NullMPI - MPI substitute library

NullMPI is a trivial (and currently incomplete) implementation of
the MPI Standard for
use as a uniprocessor replacement. Use this to port your parallel code to
machines without a MPI implementation or quick test-compiles.

NullMPI allows global communications, but does not implement
point-to-point communications to self. Timing is supported. Compilation
options allow for debug and statistics output.

Furthermore, the set of headers can be used with the static source code
checker splint (see http://splint.org/)
for portability testing.